This invention relates to novel ester compounds exhibiting a liquid crystal phase within a broader temperature range.
Liquid crystal elements utilize optical anisotropy and dielectric anisotropy of liquid crystal substances and are classified by their display modes into various types such as TN type (twisted nematic type), DS type (dynamic scattering type), guest-host type, DAP type, etc.; and the properties of liquid crystal substances suitable to their respective uses are different. However, it is common to any of such liquid crystal substances that they must be stable to moisture, air, heat, light, etc., and also they must exhibit a liquid crystal phase within as broad a temperature range as possible, centering about room temperature, and further have an optimum dielectric anisotropy value (.DELTA..epsilon.) which is varied depending on the kinds of the display elements. However, no single compounds satisfying such requirements has been found to date, and it is the present status that liquid crystal compositions obtained by mixing together several kinds of liquid crystal compounds and non-liquid crystal compounds have been used. Recently, in particular, liquid crystal display elements actuated within a temperature range from about -20.degree. C. to about 80.degree.-90.degree. C. have come to be required. Thus, liquid crystal compositions having superior actuation characteristics within a broader temperature range have been desired.
The object of the present invention is to provide novel liquid crystal compounds useful as a component of such liquid crystal compositions.